Coronaviruses had a wide range of symptoms from asymptomatic to severe illness and has caused significant morbidity and death among large population infected with this virus. To correlate CT severity score with each blood parameter like (TLC counts, Absolute neutrophil count, Absolute lymphocyte count, neutrophilic/lymphocytic ratio, quantitative D-dimer, ferritin, CRP, IL-6 and LDH). To assess diagnostic and prognostic significance of each parameter in predicting severity of disease.The present study was a 1-year prospective, a hospital-based study from 1 August 2020 to 31 July 2021 and included 100, COVID-19 confirmed cases. The clinical, radiological and laboratory reports were collected. The CT score were compared with different blood parameters. The results were analyzed statistically using correlation coefficient(r).27 patients having a CT severity score 1-10 were graded in mild category. 27 patients having CT severity score 11-15 were graded in moderate category.34 patients having CT severity score 16- 20 were graded as severe.12 patients having CT severity score 21-25 were graded as very severe. The present study showed raised TLC count > 11000 / µl in 35% patients suffering from COVID -19. Absolute neutrophil count > 7000/µl was seen in 50 % patients. 65% patients showed Absolute lymphocyte count <1000> 3.5 was seen in 83% patients. Raised D-Dimer >500 ng/ml was observed in 74 % patients. 92 % subjects showed raised Serum ferritin >150ng/ml. IL-6 >10pg/ml was seen in 92 % patients. Q-CRP >10 mg/l was seen in 97 % patients.HRCT chest severity score of patients with COVID-19 has positive correlation with various laboratory parameters and hence can be used as an indicator of disease severity. It can play a vital role in the management of COVID-19 and should be used for comprehensive evaluation.